Budget Calculator (50/30/20)
Split your income using the 50/30/20 rule: needs, wants, and savings.
About the 50/30/20 Rule
A simple budgeting framework: allocate 50% of after-tax income to needs, 30% to wants, and 20% to savings or debt repayment.
About this tool
The 50/30/20 budget rule is a simple framework for managing your money by dividing your after-tax income into three categories: 50% for needs (rent, food, utilities), 30% for wants (entertainment, dining out, hobbies), and 20% for savings and debt repayment. This Budget Calculator automates the math, instantly showing you how much to allocate to each category based on your income. It's an effective starting point for anyone seeking financial discipline without overthinking.
To use the calculator, enter your monthly or annual after-tax income—the amount that actually lands in your account after taxes and deductions. The tool automatically splits this into the three buckets and displays the exact dollar amounts you should aim for in each category. This is particularly helpful for budgeting beginners, freelancers with variable income, and anyone looking to establish a baseline spending plan before adjusting it to their personal circumstances.
Frequently Asked Questions
Code Implementation
from dataclasses import dataclass, field
from typing import List
@dataclass
class BudgetItem:
name: str
amount: float
category: str # 'need' | 'want' | 'savings'
@dataclass
class Budget:
income: float
items: List[BudgetItem] = field(default_factory=list)
def add_item(self, name: str, amount: float, category: str):
self.items.append(BudgetItem(name, amount, category))
def total_expenses(self) -> float:
return sum(i.amount for i in self.items)
def surplus(self) -> float:
return self.income - self.total_expenses()
def by_category(self) -> dict:
totals = {'need': 0.0, 'want': 0.0, 'savings': 0.0}
for item in self.items:
totals[item.category] += item.amount
return totals
def rule_50_30_20(self) -> dict:
"""Check against the 50/30/20 guideline."""
cats = self.by_category()
return {
'needs_pct': cats['need'] / self.income * 100,
'wants_pct': cats['want'] / self.income * 100,
'savings_pct': cats['savings'] / self.income * 100,
}
# Example
budget = Budget(income=5000)
budget.add_item("Rent", 1200, "need")
budget.add_item("Groceries", 400, "need")
budget.add_item("Utilities", 150, "need")
budget.add_item("Transport", 300, "need")
budget.add_item("Dining out", 250, "want")
budget.add_item("Streaming", 50, "want")
budget.add_item("Entertainment", 200, "want")
budget.add_item("Emergency fund", 500, "savings")
budget.add_item("Investments", 500, "savings")
cats = budget.by_category()
rule = budget.rule_50_30_20()
print(f"Income: ${budget.income:,.2f}")
print(f"Expenses: ${budget.total_expenses():,.2f}")
print(f"Surplus: ${budget.surplus():,.2f}")
print(f"Needs: ${cats['need']:,.2f} ({rule['needs_pct']:.1f}%, target 50%)")
print(f"Wants: ${cats['want']:,.2f} ({rule['wants_pct']:.1f}%, target 30%)")
print(f"Savings: ${cats['savings']:,.2f} ({rule['savings_pct']:.1f}%, target 20%)")
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